The invention relates to a device for removing flat objects from a stack comprising a magazine in which are stacked on edge flat objects to be serialized and a vertical destacking plate disposed directly in front of the magazine and against which the first object of the stack will be pressed, said first object of the stack being ejected in a direction perpendicular to the direction of advance of the stack of flat objects in the magazine.
The invention applies most particularly to a device for removing flat objects from a stack for a postal sorting machine operating in synchronous mode.
In contemporary destackers for postal sorting machines operating in synchronous mode, the stack of flat objects is pushed step by step toward the destacking plate only after the first object of the stack pressed against this destacking plate has been completely ejected from the destacker. The users of this type of sorting machine are seeking to be able to process an ever broader spectrum of flat objects, that is to say flat objects whose height, width and thickness dimensions vary greatly. When a very thick object is ejected from the destacker, an empty space is created between the destacking plate and the new first object of the stack to be serialized and the idea on which the invention is based is to fill this empty space as rapidly as possible so as to increase the destacking throughout.
The document DE-19545057C discloses a thickness measurement system for measuring the thickness of each flat object pressed against a destacking device, this thickness measurement serving for the feedback control of the movement of the stack of flat objects in the magazine. In this system, the thickness is found from the deflection of a swivel roller which deflection can be determined by a rotary potentiometer. Such system is not fitted to process a broader spectrum of flat objects.
Accordingly, the present invention is a device for removing flat objects from a stack comprising a magazine, in which are stacked on edge flat objects to be serialized, a destacker device vertically disposed directly in front of the magazine and a motorized means for advancing the stack of flat objects along a longitudinal direction (D) in the magazine towards said destacker device so that the first object of the stack of flat objects is pressed against the destacker device in order to be ejected from the stack of flat objects in a direction perpendicular to the direction of advance of the stack of flat objects.
The device also comprises a thickness measurement means for measuring the thickness of each ejected object. The thickness measurement serves as a feedback control for the movement of the stack of flat objects in the magazine in such a way to bring forward the movement of the stack of flat objects toward the destacker device by a distance corresponding to the thickness measurement of the ejected object.
The thickness measurement means comprises at least one pair of elastically deformable wheels made of elastomer and between which is pinched each ejected object and a pair of laser telemeters mounted between said destacking device and the pair of elastically deformable wheels.
Each elastically deformable wheel has a fixed position rotation axle and comprises a hub joined to an annular tread strip by elastically deformable circular actuate veins. Each vein has its two ends for joining to the hub and to the annular strip of the wheel which are situated on a spoke of the wheel.